Species-specific acoustic behavior will be studied by techniques of auditory neurophysiology, developmental biology, and behavior genetics. Our goal is to map the auditory pathways in terms of the structure and function of uniquely identified auditory neurons. This map will provide a basis for investigating the development of the auditory system, and neural loci that are the focus of known genetic controls on auditory behavior. The neural basis of mate-attraction and predator detection, both of which are mediated by auditory signals, will be investigated. In particular, the role of temporal pattern in species-specific mating calls will be explored by employing song-synthesis techniques in a newly developed behavioral bioassay for phonotactic behavior. The effects of auditory deprivation and deafferentation will be studied by observing their effects on the dendritic morphology of a particular identified interneuron, int-l. In particular, the factors that contribute to the compensatory growth of the dendrites of int-l will be investigated. Finally, the ability of a peripheral sensory field (in this case, the ear) to induce the CNS to develop neurons appropriate to the sensory field will be tested by making transplants of peripheral fields (ears) into homologous segments that are not normally auditory. The fate of the CNS projections of the transplanted fields will be followed at the cellular level of analysis to ascertain the amount of plasticity in neural development.